Packaging



Sept. 16, 1969 c, HUDSON ETAL 3,466,850

PACKAGING Filed April 25, 1967 4 Sheets-Sheet 1 Sept. 16,1969

Filed April 25, 1967 C. H. HUDSON ET AL PACKAGING 4 Sheets-Sheet 2 Sept. 16, 1969 c. H. HUDSON ETAL 3,465,850

PACKAGING Filed April 25, 1967 4 Sheets-Sheet 3 FIG.3.

Sept. 16, 1969 3, HUDSON ETAL 3,466,850

PACKAGING Filed April 25, 1967 4 Sheets-Sheet 4 I i --I-\ 3b 35 I United States Patent US. CI. 53-28 18 Claims ABSTRACT OF THE DISCLOSURE A method and apparatus for preparing sealable web material for use in packaging a sterilized product in which the material in sheet or tube form is passed through sterilizing means to sterilize at least its product contacting surface, the material immediately passing into a sterilized zone, from which outside air is excluded by passing pressurized sterile medium through the zone, for further treatment of the material such as tube forming, filling and/ or sealing in the zone.

This invention relates to the packaging of a sterilized product.

It is known to package products in sachets formed from a web or Webs of heat or pressure sealable material by feeding a web or a pair of webs through first sealing means which bond the longitudinal web margins together to form a tube, and second sealing means which forms spaced transverse seals along the length of the tube to produce a series of contiguous sachets, each of which has meanwhile received a product from a feed device projecting into the tube. The sachets may then be separated by slitting across the transverse seals.

When a sterilized product is packaged by the above technique, it is desirable that at the time the product is delivered to a sachet, the sachet interior should have at least the same degree of sterilization as the product, and that this degree of sterilization should be maintained until the product is sealed in the sachet.

It is an object of the present invention to provide a method and apparatus for preparing sealable web material for use in packaging a sterilized product.

The invention consists in a method of preparing sealable web material for use in packaging a sterilized product comprising progressively sterilizing a surface of the material at entry to a sterilized zone, passing the surface into the sterilized zone before it can become recontaminated, with the material itself forming a wall portion of the zone, and passing sterilized gas through the zone to maintain a sterilized condition therein.

The invention also consists in apparatus for preparing sealable web material for use in packaging a sterilized product comprising sterilizing means for progressively sterilizing a surface of the material as the material is passed therethrough, means for progressively advancing material through the sterilizing means and hence into a sterilized zone with the material forming a wall portion of said zone, and means for supplying sterilized gas to said zone to prevent external air and the like from entering the zone.

In one form of the invention, a web of sealable mate rial is moved successively through first and second sterilizing means operative respectively on opposite surfaces of the web, each surface moving from its respective sterilizing means into the sterilized zone before it can become recontaminated with a portion of the web spanning a gap 3,466,850 Patented Sept. 16, 1969 ice etween the sterilizing means to form said wall portion of the zone, its unsterilized surface being outside the zone, and the web being formed in the zone into a tube for receiving the product.

In another form of the invention, a tube formed from sealable web material is passed progressively through sterilizing means operative to sterilize the interior surface of the tube, and thence the tube passes to transverse sealing means adapted to form spaced transverse seals in the tube at a distance from the sterilizing means, the sterilized zone comprising the portion of the tube interior between the sterilizing means and the transverse sealing means into which projects a sterilized product feed device and means for passing sterilized gas through the zone towards the sterilizing means.

The invention will now be described by way of an example with reference to the packaging of sterilized milk in sachets formed from a polyethylene web in a packaging machine of the type which in operation continually draws the web in stepwise manner over a former which folds the longitudinal edges of the web over to form a tube, and is provided with longitudinal sealing means which seal the longitudinal web margins and transverse sealing means which form spaced transverse seals across the tube to produce a series of contiguous sachets, each of which has meanwhile received a predetermined quantity of milk from a filling device projecting into the tube and operative in timed relation to the operation of the sealing means and the stepwise movement of the tube through the machine to supply each sachet with its milk after the lower transverse seal is formed and before the formation of the upper seal.

Machines of this type are well known and will not be described in detail, except for those components requiring special modification or adaption to enable the machine to package a sterilized product under sterile conditions.

In the accompanying drawings:

FIGURE 1 is a diagrammatic side view of a machine of the above type having one form of sterilizing means according to the invention,

FIGURE 2 is a diagrammatic side view of a machine of the above type having another form of sterilizing means according to the invention,

FIGURE 3 is a diagrammatic front view of a machine as shown in either of FIGURES l or 2,

FIGURE 4 is an enlarged partly sectioned view of the top part of the machine as shown in FIGURE 3, and

FIGURE 5 is a diagrammatic front view of part of a machine of generally similar character to the machines of FIGURES l to 4 but having a third form of sterilizing means according to the invention.

In machines operating with an unsterilized product, it is satisfactory to draw the tube forming web off a roll mounted say at the rear of or above the machine, the web being exposed to the atmosphere throughout its passage through the machine. Where a machine is used to package a sterilized product, however, it is necessary, in order to maintain the sterilized condition of the product, that the interior of each sachet be at least as sterile as the product when it is filled and up until it is sealed. This is accomplished according to one embodiment of the invention by drawing the web from a roll through sterilizing means and thence through a sterilized zone which extends from the sterilizing means at least to the tube forming and longitudinal sealing means so that the sterilized web is maintained in a sterilized condtion whilst it proceeds through the tube forming means and longitudinal sealing means after which it can leave the sterilized zone after the completion of the tube forming operation by sealing the longitudinal margins together, sterility of the tube interior is ensured. Moreover, al-

though strictly only the interior of the tube need be sterilized, it is nevertheless necessary with this technique to sterilize both surfaces of the web, to prevent contamination of one surface by the other during passage of the Web from the sterilizing means through the sterilized zone.

The sterilized zone comprises (a) a chamber 1 substantially sealed to the atmosphere and constructed to incorporate the tube forming means 2 and mechanism for drawing the web from its roll through the machine, (b) an extension of the chamber formed in operation by the interior of the sealed tube 3 as it issues from the longitudinal sealing means and into which a filling device (not shown in FIGURES 1 and 2.) projects, and (c) a reservoir 5 for the filling device. The web enters the chamber, as will be described, immediately on passing through the sterilizing means and leaves the chamber after being formed into a tube. In operation cool sterilized slightly pressurized air is blown through the chamber to maintain its sterility and prevent atmospheric air entering the chamber at the web inlets, tube outlet, and other crevices.

In one form of the invention, as shown in FIGURE 1, the first and second sterilizing means each comprise a substantially Wedge-shaped hollow water cooled guide (6 and 6a repectively) disposed with its apex to one side and the apex angle of the wedge being about 30 and means, for example a gas jet tube 7 and 7a respectively, for applying of a substantially homogeneous low intensity ribbon of flame across and beyond the entire width of the web directly under the apex of the wedge. The guides of the first and second sterilizing means are positioned in an opening 8 of the sterilized chamber, and the arrangement is such that in operation a motor driven drive roll 9 and gripping roll 10 in the chamber draws the web 11 from its supply roll 12 outside the chamber around the wedge shaped guide 6 of the first sterilizing means and thence around the wedge shaped guide 6a of the second sterilizing means. As the web passes up over the apex or nose of the first guide which has a very small radius, its outer surface is sterilized by the flame from the gas tube 7 and on passing through the flame the web is immediately turned away from the flame through the sharp angle of the guide apex and immediately enters the sterilized chamber as it turns around the apex of the guide, a wall 13 of the sterilized chamber terminating immediately above the apex of the guide so that there is a small gap between the wall and the guide for the web to enter the chamber and through which gap cool sterilized air from the chamber is blown to prevent the ingress of atmospheric air. The other unsterilized surface of the web now travels along the top of the guide 6 which is outside the sterilized chamber, and is subjected to cooling from the guide.

The web then bridges the gap between the first and second sterilizing guides and in this gap the web itself forms a wall of the sterilized chamber, its sterilized surface being within the chamber and its unsterilized surface outside the chamber, and the web then passes around the second sterilizing guide 6a towards the apex thereof, with its sterilized surface against the guide (which is within the sterilized chamber) and its unsterilized surface exposed to atmosphere (i.e. outside the sterilized chamber.) Immediately under the apex of the second guide the web passes through the flame from the second gas tube, to sterilize the outer surface and is then immediately turned away from the flame around the apex of the cooled guide and passes over its upper surface which is in the sterilized chamber, another wall 14 of the chamber terminating immediately above the apex of the second guide to provide another small gap for the web to enter the chamber. Both surfaces of the web in the chamber are now sterilized and pass off the upper surface of the second guide around an idler roll 15 in the chamber to the drive and gripper rolls 9 and 10.

It will be seen that by the above arrangement, the unsterilized surface portion of the web between the first and second gas tubes remains outside the sterilized zone, whilst the sterilized surface portion between the tubes is in the sterilized zone, and after the respective surfaces are sterilized these immediately pass into the sterilized zone before they can become re-contaminated by the atmosphere.

Each sterilizing means functions to sterilize a surface of the web by direct heat from a naked flame, whilst the other surface is subject to cooling and whilst the Web is passed through the flame under tension and then immediately turned away from the flame through a sharp angle whilst being subjected to further cooling. This arrangement minimizes the possibility of web distortion by heat from the flame. The angles of the guide apexes have been described as 30 but these could be varied up to or below 30.

As mentioned above, the tube and sachet forming means of the machine operate with a step-wise motion of the Web. Obviously, the web cannot be passed through the naked flames of the sterilizing means in this manner unless the flames are moved away from the web or extinguished during each halt in its motion and therefore according to another feature of the invention, means are provided for driving the drive and gripper rollers 9 and 10 in the sterilizing chamber continuously, whereby the web can be drawn off the supply roll and passed through the sterilizing means continuously, and mechanism in the form of a freely supported jockey roll 16 is provided following the drive and grip rolls for taking up the web slack during halts in the stepwise motion of the web through the tube and sachet forming means. The web passes under the jockey roll which is freely supported in vertical guides so that it moves down to take up the slack during said halts, and moves up to supply web during its stepwise movements. Control means such as limit switches (not shown) are provided to co-ordinate the stepwise and continuous drives to the web by controlling the speed of the drive and gripper rollers in accordance with the movements of the jockey roll.

The gas tubes are mounted on pivotal brackets controlled by a common pneumatic piston and cylinder assembly so that these can be moved away from the web when the machine is inoperative.

In an alternative form of the invention (shown in FIGURE 2) each sterilizing means takes the form of a high frequency, high voltage spark discharge mechanism 18 and 18a having one or more sterilizing stations. Each sterilizing station comprises a metal electrode strip mounted on suitable insulators and positioned approximately one to two millimetres from the surface of the web being sterilized, which latter is passed over a freely rotatable plastic roller having internal aluminium laminations earthed to the frame of the machine through slip ring contacts.

In operation, a high voltage spark is generated alternatively at each station and bridges the gap between the electrode and the aluminum strip in the roller. These sparks, with the ozone they produce, sterilize the web.

The plastic rollers 17 and 17a of the first and second sterilizing means respectively are positioned at the entrance to the sterilized chamber in like manner to the sterilizing guides of the first embodiment, with one surface of the web being sterilized by the first sterilizing means and then entering the chamber whilst the other surface contacting the first plastic roller remains outside the chamber, and a portion of the web bridge the gap between the plastic rollers and forms a wall of the sterilized chamber with its sterilized surface in the chamber and its unsterilized surface outside the chamber in like manner to the first embodiment. The other surface of the web is then sterilized by the second sterilizing means and then immediately enters the chamber. In this case, however, it is possible to pass the Web through the sterilizing means in stepwise manner, the spark discharge devices being inoperative during halts in the web travel so that the continuously driven roll and jockey roll in the chamber can be dispensed with.

To minimize the possibility of ozone formed by the spark discharge devices from reaching the milk, the sterilized chamber may be compartmented by means of a bafiie 19 through a slit 20, in which the web passes with small clearance. The cool sterilized air is blown through the slit from the filling end of the machine to prevent ozone entering the compartment of the chamber at this end.

As mentioned above, the sterilizing chamber need only extend up to and include the tube forming means and the longitudinal sealing means since after the web is formed into a sealed tube atmospheric air cannot come into contact with its interior surface. Therefore, after the tube forming means and longitudinal sealing means, the tube leaves the sterilizing chamber through an opening 21 having small clearance around the tube, through which in operation the cool sterilized air blown through the chamber issues.

The filling device according to another feature of the invention comprises a filling tube 26 (not shown) projecting into the sterilized chamber through a hermetic seal at 27, and a vertically reciprocable valve rod 22 with a valve head 28 adapted to seat against the lower end of the tube. The tube is positioned so that its lower end projects into the web tube as this is formed into a sachet and means are provided external to the sterilized chamber to actuate the valve for a preset period in timed relation to the stepwise movement of the Web so that each sachet receives the required amount of milk. This means takes the form of a diaphragm sealed compartment 23 on top of the milk tank 5 connected with the sterilized milk feed tube and with the sterilized chamber through the filling tube, the top of which opens into the tank. The upper end of the valve rod 22 extends through the tank into compartment 23 and contacts the inner sterilized face of the diaphragm 24 and the rod is moved to open the valve by external pressure from, say, an air motor 25 acting on the outer face of the diaphragm.

Prior to operation of the machine, it is necessary to sterilize thoroughly the interior of the sterilized chamber, the tube forming means, the interior of the milk feed tank and the interior, and exterior of the filling tube before the web is passed into the machine. This may for example by accomplished by pre-heating the chamber and these associated components with the filling valve open, by hot sterilized air at a temperature of about 170 C., and to minimize the heating-up time of the chamber and associated parts it is convenient to heat insulate the chamber interior.

During sterilization it is necessary to have a web or like film threaded through the machine, and in the case of heat sterilization, if the normal operating web has a lower melting temperature than the sterilizing temperature, then according to a still further feature of the invention there is provided a leader strip of high temperature resistant material, one end of which is formed into a sealed tube also sealed at the lower end and conforming in dimensions to the tube produced by the machine, the strip opening out into a flat strip conforming in dimensions to the web. The strip is fed through the machine in the reverse direction before the heat sterilization so that its tube portion encloses the filling tube and seals the chamber outlet, and so that its opened-out portion passes through the chamber and sterilizing means with its free end projecting at the rear of the machine for attachment to the front end of the operating web.

The machine is heat sterilized with the leader strip positioned thus, its tube portion forming the extension of the chamber normally formed by the web tube and after sterilization the hot sterilizing air circulating through the chamber is replaced by the cool sterilized air used during normal operation. The sterilizing means are actuated and the leader strip with attached web is fed through the machine in the forward direction, so that there is a continuous supply of film through the sterilized chamber. If the leader strip is of unsealable material an external pull-away sock may be provided to surround the filling device and leader strip and prevent atmospheric air contaminating the filling device during passage of the leader strip through the machine. During operation it is necessary to provide an unbroken supply of web to maintain the sterilization in the sterilized zone, so that web supply rolls should be joined end to end.

FIGURE 5 illustrates diagrammatically another embodiment of the invention which employs a machine of generally similar character to those described in relation to FIGURES 1 to 4 except that the sterilized chamber is dispensed with and only the internal product contacting surface of the web material is sterilized after the Web has been formed into a tube.

The web 30 received from a supply roll is drawn in stepwise manner over tube forming means, and longitudinal sealing means 31. In this arrangement, the web margins are brought together in abutting relation and an external longitudinal strip of sealing material is laid over the join and bonded to the web on each side thereof by the sealing means. From the longitudinal sealing means the tube passes through a sterilizer 32 which sterilizes its internal surface, and hence to transverse sealing means 33 which forms spaced transverse seals in the tube to provide a series of contiguous sachets each of which has meanwhile received a supply of milk from a milk feed device 34 supplied from a tank not shown in an identical manner to the feed arrangement of the previous embodiments. The sealing means 33 which alternatively grip and release the tube may be made to reciprocate vertically as a means of drawing the web material through the machine in stepwise manner.

The sterilizing means 32 comprises a spark discharge arrangement operating on the same principle as the sterilizing means described in relation to the FIGURE 2 embodiment. Internally of the tube there are provided a pair of oppositely helically wound ribbon electrodes 35 and 36 mounted between non-conducting end plates 37 and 38 through which the milk tube 34 and a tube 39 for blowing cool sterilized air pass with a tight fit, these also being made of non-conducting material such as epoxy resin. Electrical connections 40 and 41 for the electrodes pass up through the web tube. The sterilizing means is completed by an outer surrounding dielectric cylinder 42 closely surrounding the electrodes and including a thin earthed cylindrical aluminium insert 43. In operation, high voltage sparks are caused to run up and down electrodes 35 and 36 during movement of the web tube to sterilize its interior surface, the sterilizing means being inoperative during the pauses in the web travel.

In this embodiment of the invention the sterilized zone comprises the sealed interior of the web tube between its lower transverse seal and the end plate 38 so that the tube itself forms a wall portion of the zone. During continuous operation of the machine the tube will always have a seal at its lower end and cool sterilized air is continuously blown into the sterilized zone through tube 39 to maintain the zone in a sterilized condition and prevent ozone formed by the spark discharge device from entering the zone. This is accomplished because an upward flow of cool pressurized air is produced which bores through the gap between the web tube and the lower plate 38 thereby preventing ozone in the sterilizing means entering the sterilized zone. The upward flow of air and build-up of pressure within the sterilizer also presses the web tube outwardly against sleeve 42.

To initiate operation of the machine, it is again necessary to pre-sterilize the interior of the feed device 34 and tube 39 and this can be efiected in like manner to the earlier embodiments, again using a heat resistant leader strip to commence operation of the machine.

We claim:

1. A method of preparing sealable web material for use in packaging a sterilized product comprising progressively sterilizing a surface of the material at entry to a sterilized zone, passing the surface into the sterilized zone before it can become recontaminated with the material itself forming a wall portion of the zone, and passing sterilized medium through the zone to prevent external air and the like from entering the zone, said method being characterized in that a web of sealable material is moved successively through first and second sterilizing means operative respectively on opposite surfaces of the web, each surface moving from its respective sterilizing means into the sterilized zone before it can become recontaminated with a portion of the web spanning a gap between the sterilizing means to form said wall portion of the zone, its unsterilized surface being outside the zone, and the web being formed in the zone into a tube for receiving the product.

2. A method as claimed in claim 1 in which sterilization of each surface is achieved by subjecting the surface to flaming whilst its other surface is cooled.

3. A method as claimed in claim 2 in which the Web is turned sharply away from the flame immediately on passing therethrough.

4. A method as claimed in claim 1 in which sterilization of each surface is achieved by subjecting the surface to a high voltage spark discharge.

5. A method as claimed in claim 1 in which pressurized cool sterilized air is passed through the sterilized zone to issue through a crevice in the zone wall and prevent ingress of contaminated air and the like.

6. A method as claimed in claim 1 in which the zone is pre-sterilized by passing hot sterilizing medium therethrough.

7. A method as claimed in claim 6 in which the zone is pre-sterilized with a heat resistant leader strip forming the wall portion of the zone later formed by the Web material, with an end of the leader strip being joined to the web material, and after pre-sterilization of the zone said hot sterilizing medium is replaced by said sterilized medium and the leader strip is advanced through the sterilizing means and sterilized zone followed by the web material.

8. A method as claimed in claim 1 in which the web material is used by packaging sterilized milk.

9. A method as claimed in claim 1 in which the web material is polyethylene.

10. A method of preparing sealable web material for use in packaging a sterilized product comprising progressively sterilizing a surface of the material at entry to a sterilized zone, passing the surface into the sterilized zone before it can become recontaminated with the material itself forming a wall portion of the zone, and passing sterilized medium through the zone to prevent external air and the like from entering the zone, said method being characterized in that a tube formed from the sealable web material is passed through sterilizing means operative to sterilize the interior surface of the tube by means of a high voltage spark discharge, the tube then passing to transverse sealing means adapted to form spaced transverse seals along the tube, the sterilized surface forming a portion of the tube interior between the sterilizing means and the transverse sealing means into which portion of the tube projects a sterilized product feed device and means for passing sterilized gas through the zone.

11. Apparatus for preparing sealable web material for use in packaging a sterilized product comprising sterilizing means for progressively sterilizing a surface of the material as the material is passed therethrough, means for progressively passing the material through the sterilizing means and hence into a sterilized zone with the material forming a wall portion of said zone, and means for supplying sterilized medium to said zone to prevent ingress of external air and the like, said sterilizing means comprising first and second sterilizing means adapted respectively to sterilize opposite surfaces of a Web as the web is passed progressively through the sterilizing means, means defining said zone capable of maintaining each said surface in a sterilized condition as the surfaces pass from the sterilizing means, the first and second sterilizing means being spaced apart at an entrance to the zone to allow a portion of the web to span the gap between the first and second sterilizing means and form said Wall portion of the zone with its unsterilized surface outside the zone, and means within the zone for forming the web into a tube for receiving the product.

12. Apparatus as claimed in claim 11 in which the first and second sterilizing means each comprise means for subjecting one surface of the web to flaming whilst simultaneously subjecting the other surface of the web to cooling.

13. Apparatus as claimed in claim 12 in which each sterilizing means includes means for turning the web through a sharp angle immediately after passage through the flaming means.

14. Apparatus as claimed in claim 13 in which each sterilizing means comprises flame producing means adjacent the nose of a wedge shaped cooling guide for the web.

15. Apparatus as claimed in claim 11 in which the first and second sterilizing means each comprise means for subjecting one surface of the web to sterilization by high voltage spark discharge means.

16. Apparatus as claimed in claim 15 in which each sterilizing means comprises a rotatable dielectric guide roller for the web, said roller having an earthed internal conducting lamination, and a pair of electrodes spaced outwardly from the roller surface and circumferentially from each other around the roller, said electrodes being adapted to alternately discharge a high voltage spark during movement of the web with the roller.

17. Apparatus for preparing sealable web material for use in packaging a sterilized product comprising sterilizing means for progressively sterilizing the interior surface of a tube formed from said material as the tube is passed through said sterilizing means, means for progressively passing the tube through the sterilizing means and hence into a sterilized zone with the tube material forming a wall portion of said zone, transverse seal forming means adapted to form spaced transverse seals along the tube at a position spaced from the sterilizing means whereby in operation the tube interior between the sterilizing means and the seal forming means forms said zone, a sterilized product feed device projecting into said zone between the sterilizing means and the transverse seal forming means, and sterilized medium supply means projecting into said zone between the sterilizing means and the seal forming means for supplying sterilized medium to said zone to prevent ingress of external air and the like, said apparatus being characterized in that the sterilizing means comprises high voltage spark discharge generating means.

18. Apparatus as claimed in claim 17 in which the sterilizing means comprises a pair of diametrically opposed helically wound strip electrodes, a dielectric cylinder surrounding said electrodes with small clearance, and an earthed conducting lamination in said cylinder.

References Cited UNITED STATES PATENTS 3,055,731 9/1962 Loliger. 3,086,336 4/1963 Rausing et al. 53180 3,164,936 1/1965 Liiliger 53-480 THERON E. CONDON, Primary Examiner E. F. DESMOND, Assistant Examiner US. Cl. X.R. 2l-?102; 53--180 

